1. Technical Field
The present invention relates to an antitheft apparatus for an automotive vehicle for preventing the vehicle from being stolen by use of an ID (identification) number allocated to each ignition key, and in particular to a method of registering an ID number of an ignition key to the antitheft apparatus.
2. Description of the Related Art
An antitheft apparatus for an automotive vehicle has been known. In this antitheft apparatus, a transponder is buried at a head portion of an ignition key, and a specific ID number is stored in the transponder. When the ignition key is inserted into a key hole of a key cylinder and then rotated to a start position to drive an engine of the vehicle, the ID number is read from the ignition key and then collated with a plurality of ID numbers already registered in the antitheft apparatus. Here, if the ID number of the key now used has been already registered in the antitheft apparatus, the engine can be started. On the other hand, if not registered, the engine cannot be started for prevention of vehicle from being stolen.
In the conventional antitheft apparatus, the ID number has been registered as follows: First, a diagnostic tester is connected to the antitheft apparatus, and a register mode switch is turned on to set the antitheft apparatus to a register mode. After that, the key is inserted into an ignition key cylinder and then rotated to an ignition-on (IGN ON) position. Under these conditions, since an ID number specific to the inserted key is read and then stored in a non-volatile memory of the antitheft apparatus. The above-mentioned procedure is repeated. When the repeated procedure reaches the maximum registration number N, the register mode is released automatically, so that N-units of keys having different ID numbers can be registered, respectively.
In the conventional antitheft apparatus, however, there exists a problem in that once the antitheft apparatus is set to the ID number register mode, the register mode cannot be released until the maximum ID number N of the ignition keys are registered in the antitheft apparatus.